// DeflaterOutputStream.cs
//
// Copyright (C) 2001 Mike Krueger
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
// 
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.

// HISTORY
//	22-12-2009	DavidPierson	Added AES support

using System;
using System.IO;
using System.Security.Cryptography;
using ICSharpCode.SharpZipLib.Encryption;

#if !NETCF_1_0

#endif

namespace ICSharpCode.SharpZipLib.Zip.Compression.Streams
{
    /// <summary>
    ///     A special stream deflating or compressing the bytes that are
    ///     written to it.  It uses a Deflater to perform actual deflating.<br />
    ///     Authors of the original java version : Tom Tromey, Jochen Hoenicke
    /// </summary>
    public class DeflaterOutputStream : Stream
    {
        #region Constructors

        /// <summary>
        ///     Creates a new DeflaterOutputStream with a default Deflater and default buffer size.
        /// </summary>
        /// <param name="baseOutputStream">
        ///     the output stream where deflated output should be written.
        /// </param>
        public DeflaterOutputStream(Stream baseOutputStream)
            : this(baseOutputStream, new Deflater(), 512)
        {
        }

        /// <summary>
        ///     Creates a new DeflaterOutputStream with the given Deflater and
        ///     default buffer size.
        /// </summary>
        /// <param name="baseOutputStream">
        ///     the output stream where deflated output should be written.
        /// </param>
        /// <param name="deflater">
        ///     the underlying deflater.
        /// </param>
        public DeflaterOutputStream(Stream baseOutputStream, Deflater deflater)
            : this(baseOutputStream, deflater, 512)
        {
        }

        /// <summary>
        ///     Creates a new DeflaterOutputStream with the given Deflater and
        ///     buffer size.
        /// </summary>
        /// <param name="baseOutputStream">
        ///     The output stream where deflated output is written.
        /// </param>
        /// <param name="deflater">
        ///     The underlying deflater to use
        /// </param>
        /// <param name="bufferSize">
        ///     The buffer size in bytes to use when deflating (minimum value 512)
        /// </param>
        /// <exception cref="ArgumentOutOfRangeException">
        ///     bufsize is less than or equal to zero.
        /// </exception>
        /// <exception cref="ArgumentException">
        ///     baseOutputStream does not support writing
        /// </exception>
        /// <exception cref="ArgumentNullException">
        ///     deflater instance is null
        /// </exception>
        public DeflaterOutputStream(Stream baseOutputStream, Deflater deflater, int bufferSize)
        {
            if (baseOutputStream == null)
            {
                throw new ArgumentNullException("baseOutputStream");
            }

            if (baseOutputStream.CanWrite == false)
            {
                throw new ArgumentException("Must support writing", "baseOutputStream");
            }

            if (deflater == null)
            {
                throw new ArgumentNullException("deflater");
            }

            if (bufferSize < 512)
            {
                throw new ArgumentOutOfRangeException("bufferSize");
            }

            baseOutputStream_ = baseOutputStream;
            buffer_ = new byte[bufferSize];
            deflater_ = deflater;
        }

        #endregion

        #region Public API

        /// <summary>
        ///     Finishes the stream by calling finish() on the deflater.
        /// </summary>
        /// <exception cref="SharpZipBaseException">
        ///     Not all input is deflated
        /// </exception>
        public virtual void Finish()
        {
            deflater_.Finish();
            while (!deflater_.IsFinished)
            {
                int len = deflater_.Deflate(buffer_, 0, buffer_.Length);
                if (len <= 0)
                {
                    break;
                }

#if NETCF_1_0
				if ( keys != null ) {
#else
                if (cryptoTransform_ != null)
                {
#endif
                    EncryptBlock(buffer_, 0, len);
                }

                baseOutputStream_.Write(buffer_, 0, len);
            }

            if (!deflater_.IsFinished)
            {
                throw new SharpZipBaseException("Can't deflate all input?");
            }

            baseOutputStream_.Flush();

#if NETCF_1_0
			if ( keys != null ) {
				keys = null;
			}
#else
            if (cryptoTransform_ != null)
            {
#if !NET_1_1 && !NETCF_2_0
                if (cryptoTransform_ is ZipAESTransform)
                {
                    AESAuthCode = ((ZipAESTransform) cryptoTransform_).GetAuthCode();
                }
#endif
                cryptoTransform_.Dispose();
                cryptoTransform_ = null;
            }
#endif
        }

        /// <summary>
        ///     Get/set flag indicating ownership of the underlying stream.
        ///     When the flag is true <see cref="Close"></see> will close the underlying stream also.
        /// </summary>
        public bool IsStreamOwner
        {
            get { return isStreamOwner_; }
            set { isStreamOwner_ = value; }
        }

        /// <summary>
        ///     Allows client to determine if an entry can be patched after its added
        /// </summary>
        public bool CanPatchEntries
        {
            get { return baseOutputStream_.CanSeek; }
        }

        #endregion

        #region Encryption

        private string password;

#if NETCF_1_0
		uint[] keys;
#else
        private ICryptoTransform cryptoTransform_;

        /// <summary>
        ///     Returns the 10 byte AUTH CODE to be appended immediately following the AES data stream.
        /// </summary>
        protected byte[] AESAuthCode;
#endif

        /// <summary>
        ///     Get/set the password used for encryption.
        /// </summary>
        /// <remarks>When set to null or if the password is empty no encryption is performed</remarks>
        public string Password
        {
            get { return password; }
            set
            {
                if ((value != null) && (value.Length == 0))
                {
                    password = null;
                }
                else
                {
                    password = value;
                }
            }
        }

        /// <summary>
        ///     Encrypt a block of data
        /// </summary>
        /// <param name="buffer">
        ///     Data to encrypt.  NOTE the original contents of the buffer are lost
        /// </param>
        /// <param name="offset">
        ///     Offset of first byte in buffer to encrypt
        /// </param>
        /// <param name="length">
        ///     Number of bytes in buffer to encrypt
        /// </param>
        protected void EncryptBlock(byte[] buffer, int offset, int length)
        {
#if NETCF_1_0
			for (int i = offset; i < offset + length; ++i) {
				byte oldbyte = buffer[i];
				buffer[i] ^= EncryptByte();
				UpdateKeys(oldbyte);
			}
#else
            cryptoTransform_.TransformBlock(buffer, 0, length, buffer, 0);
#endif
        }

        /// <summary>
        ///     Initializes encryption keys based on given <paramref name="password" />.
        /// </summary>
        /// <param name="password">The password.</param>
        protected void InitializePassword(string password)
        {
#if NETCF_1_0
			keys = new uint[] {
				0x12345678,
				0x23456789,
				0x34567890
			};
			
			byte[] rawPassword = ZipConstants.ConvertToArray(password);
			
			for (int i = 0; i < rawPassword.Length; ++i) {
				UpdateKeys((byte)rawPassword[i]);
			}
			
#else
            var pkManaged = new PkzipClassicManaged();
            byte[] key = PkzipClassic.GenerateKeys(ZipConstants.ConvertToArray(password));
            cryptoTransform_ = pkManaged.CreateEncryptor(key, null);
#endif
        }

#if !NET_1_1 && !NETCF_2_0
        /// <summary>
        ///     Initializes encryption keys based on given password.
        /// </summary>
        protected void InitializeAESPassword(ZipEntry entry, string rawPassword,
            out byte[] salt, out byte[] pwdVerifier)
        {
            salt = new byte[entry.AESSaltLen];
            // Salt needs to be cryptographically random, and unique per file
            if (_aesRnd == null)
                _aesRnd = new RNGCryptoServiceProvider();
            _aesRnd.GetBytes(salt);
            int blockSize = entry.AESKeySize/8; // bits to bytes

            cryptoTransform_ = new ZipAESTransform(rawPassword, salt, blockSize, true);
            pwdVerifier = ((ZipAESTransform) cryptoTransform_).PwdVerifier;
        }
#endif

#if NETCF_1_0
		
    /// <summary>
    /// Encrypt a single byte 
    /// </summary>
    /// <returns>
    /// The encrypted value
    /// </returns>
		protected byte EncryptByte()
		{
			uint temp = ((keys[2] & 0xFFFF) | 2);
			return (byte)((temp * (temp ^ 1)) >> 8);
		}

		/// <summary>
		/// Update encryption keys 
		/// </summary>		
		protected void UpdateKeys(byte ch)
		{
			keys[0] = Crc32.ComputeCrc32(keys[0], ch);
			keys[1] = keys[1] + (byte)keys[0];
			keys[1] = keys[1] * 134775813 + 1;
			keys[2] = Crc32.ComputeCrc32(keys[2], (byte)(keys[1] >> 24));
		}
#endif

        #endregion

        #region Deflation Support

        /// <summary>
        ///     Deflates everything in the input buffers.  This will call
        ///     <code>def.deflate()</code> until all bytes from the input buffers
        ///     are processed.
        /// </summary>
        protected void Deflate()
        {
            while (!deflater_.IsNeedingInput)
            {
                int deflateCount = deflater_.Deflate(buffer_, 0, buffer_.Length);

                if (deflateCount <= 0)
                {
                    break;
                }
#if NETCF_1_0
				if (keys != null) 
#else
                if (cryptoTransform_ != null)
#endif
                {
                    EncryptBlock(buffer_, 0, deflateCount);
                }

                baseOutputStream_.Write(buffer_, 0, deflateCount);
            }

            if (!deflater_.IsNeedingInput)
            {
                throw new SharpZipBaseException("DeflaterOutputStream can't deflate all input?");
            }
        }

        #endregion

        #region Stream Overrides

        /// <summary>
        ///     Gets value indicating stream can be read from
        /// </summary>
        public override bool CanRead
        {
            get { return false; }
        }

        /// <summary>
        ///     Gets a value indicating if seeking is supported for this stream
        ///     This property always returns false
        /// </summary>
        public override bool CanSeek
        {
            get { return false; }
        }

        /// <summary>
        ///     Get value indicating if this stream supports writing
        /// </summary>
        public override bool CanWrite
        {
            get { return baseOutputStream_.CanWrite; }
        }

        /// <summary>
        ///     Get current length of stream
        /// </summary>
        public override long Length
        {
            get { return baseOutputStream_.Length; }
        }

        /// <summary>
        ///     Gets the current position within the stream.
        /// </summary>
        /// <exception cref="NotSupportedException">Any attempt to set position</exception>
        public override long Position
        {
            get { return baseOutputStream_.Position; }
            set { throw new NotSupportedException("Position property not supported"); }
        }

        /// <summary>
        ///     Sets the current position of this stream to the given value. Not supported by this class!
        /// </summary>
        /// <param name="offset">The offset relative to the <paramref name="origin" /> to seek.</param>
        /// <param name="origin">The <see cref="SeekOrigin" /> to seek from.</param>
        /// <returns>The new position in the stream.</returns>
        /// <exception cref="NotSupportedException">Any access</exception>
        public override long Seek(long offset, SeekOrigin origin)
        {
            throw new NotSupportedException("DeflaterOutputStream Seek not supported");
        }

        /// <summary>
        ///     Sets the length of this stream to the given value. Not supported by this class!
        /// </summary>
        /// <param name="value">The new stream length.</param>
        /// <exception cref="NotSupportedException">Any access</exception>
        public override void SetLength(long value)
        {
            throw new NotSupportedException("DeflaterOutputStream SetLength not supported");
        }

        /// <summary>
        ///     Read a byte from stream advancing position by one
        /// </summary>
        /// <returns>The byte read cast to an int.  THe value is -1 if at the end of the stream.</returns>
        /// <exception cref="NotSupportedException">Any access</exception>
        public override int ReadByte()
        {
            throw new NotSupportedException("DeflaterOutputStream ReadByte not supported");
        }

        /// <summary>
        ///     Read a block of bytes from stream
        /// </summary>
        /// <param name="buffer">The buffer to store read data in.</param>
        /// <param name="offset">The offset to start storing at.</param>
        /// <param name="count">The maximum number of bytes to read.</param>
        /// <returns>The actual number of bytes read.  Zero if end of stream is detected.</returns>
        /// <exception cref="NotSupportedException">Any access</exception>
        public override int Read(byte[] buffer, int offset, int count)
        {
            throw new NotSupportedException("DeflaterOutputStream Read not supported");
        }

        /// <summary>
        ///     Asynchronous reads are not supported a NotSupportedException is always thrown
        /// </summary>
        /// <param name="buffer">The buffer to read into.</param>
        /// <param name="offset">The offset to start storing data at.</param>
        /// <param name="count">The number of bytes to read</param>
        /// <param name="callback">The async callback to use.</param>
        /// <param name="state">The state to use.</param>
        /// <returns>Returns an <see cref="IAsyncResult" /></returns>
        /// <exception cref="NotSupportedException">Any access</exception>
        public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback callback,
            object state)
        {
            throw new NotSupportedException("DeflaterOutputStream BeginRead not currently supported");
        }

        /// <summary>
        ///     Asynchronous writes arent supported, a NotSupportedException is always thrown
        /// </summary>
        /// <param name="buffer">The buffer to write.</param>
        /// <param name="offset">The offset to begin writing at.</param>
        /// <param name="count">The number of bytes to write.</param>
        /// <param name="callback">The <see cref="AsyncCallback" /> to use.</param>
        /// <param name="state">The state object.</param>
        /// <returns>Returns an IAsyncResult.</returns>
        /// <exception cref="NotSupportedException">Any access</exception>
        public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback,
            object state)
        {
            throw new NotSupportedException("BeginWrite is not supported");
        }

        /// <summary>
        ///     Flushes the stream by calling <see cref="DeflaterOutputStream.Flush">Flush</see> on the deflater and then
        ///     on the underlying stream.  This ensures that all bytes are flushed.
        /// </summary>
        public override void Flush()
        {
            deflater_.Flush();
            Deflate();
            baseOutputStream_.Flush();
        }

        /// <summary>
        ///     Calls <see cref="Finish" /> and closes the underlying
        ///     stream when <see cref="IsStreamOwner"></see> is true.
        /// </summary>
        public override void Close()
        {
            if (!isClosed_)
            {
                isClosed_ = true;

                try
                {
                    Finish();
#if NETCF_1_0
					keys=null;
#else
                    if (cryptoTransform_ != null)
                    {
                        GetAuthCodeIfAES();
                        cryptoTransform_.Dispose();
                        cryptoTransform_ = null;
                    }
#endif
                }
                finally
                {
                    if (isStreamOwner_)
                    {
                        baseOutputStream_.Close();
                    }
                }
            }
        }

        private void GetAuthCodeIfAES()
        {
#if !NET_1_1 && !NETCF_2_0
            if (cryptoTransform_ is ZipAESTransform)
            {
                AESAuthCode = ((ZipAESTransform) cryptoTransform_).GetAuthCode();
            }
#endif
        }

        /// <summary>
        ///     Writes a single byte to the compressed output stream.
        /// </summary>
        /// <param name="value">
        ///     The byte value.
        /// </param>
        public override void WriteByte(byte value)
        {
            var b = new byte[1];
            b[0] = value;
            Write(b, 0, 1);
        }

        /// <summary>
        ///     Writes bytes from an array to the compressed stream.
        /// </summary>
        /// <param name="buffer">
        ///     The byte array
        /// </param>
        /// <param name="offset">
        ///     The offset into the byte array where to start.
        /// </param>
        /// <param name="count">
        ///     The number of bytes to write.
        /// </param>
        public override void Write(byte[] buffer, int offset, int count)
        {
            deflater_.SetInput(buffer, offset, count);
            Deflate();
        }

        #endregion

        #region Instance Fields

        /// <summary>
        ///     This buffer is used temporarily to retrieve the bytes from the
        ///     deflater and write them to the underlying output stream.
        /// </summary>
        private readonly byte[] buffer_;

        /// <summary>
        ///     The deflater which is used to deflate the stream.
        /// </summary>
        protected Deflater deflater_;

        /// <summary>
        ///     Base stream the deflater depends on.
        /// </summary>
        protected Stream baseOutputStream_;

        private bool isClosed_;

        private bool isStreamOwner_ = true;

        #endregion

        #region Static Fields

#if !NET_1_1 && !NETCF_2_0
        // Static to help ensure that multiple files within a zip will get different random salt
        private static RNGCryptoServiceProvider _aesRnd;
#endif

        #endregion
    }
}